This proposal is to establish a multi-user flow cytometry facility at the Jefferson Cancer Institute, to support the research activities of several members of the Department of Microbiology and Immunology and of that of Medicine. To this purpose, we request funds to purchase a Coulter EPICS Elite flow cytofluorimeter. Currently, Thomas Jefferson University does not possess a facility of this type nor a cell sorter/analyzer dedicated to research activities. Two analyzers exist on campus: an Epics-C in the Division of Medicine Oncology, and a FACScan in the Hospital Clinical Pathology Laboratories. The Epics-C is not an up-to-date instrument, can not satisfactorily perform multicolor analysis, lacks U.V. capabilities, and can not be updated. The FACScan is dedicated to the Clinical Laboratory and can be used for research activities only as time permits. Neither machine has cell sorting capabilities. Flow cytometry technology has rapidly progressed and several techniques required by the scientific projects of our group require the EPICS Elite instrument. This instrument will allow us to establish a multi-user facility and will provide it with the ability to perform simple immunofluorescence experiments, as well as to sort cells with high purity and velocity, to perform 3 and 4 color immunofluorescence analysis, efficient use of dyes requiring U.V. activation (e.g. Indo-1 and Hoechst 33342), and simultaneous analysis of cell cycle by DNA staining and surface antigens by two-color immunofluorescence. We propose to use the EPICS Elite for a variety of projects, including cellular immunology, hematology, control of cell growth, and tumor biology.